Abstract:Based on morphological data, a phylogenetic analysis was performed to study the circumscription and infrageneric classification of the genus Lysimachia. Parsimony analysis showed that Lysimachia was paraphyletic, with L. crispidens as the sister group to all the other samplings, including those small genera of the tribe Lysimachieae. The monophylies of subgen. Idiophyton, subgen. Lysimachiopsis and subgen. Palladia were supported, while subgen. Lysimachia was found to be paraphyletic. The subgen. Naumburoia，whose status being controversial，was nested within the main simachia group． Subgen．Seleucia，however，was deviated and grouped with Trientatis．It iS noted that in this study most morphological characters are homoplasious and hence only some internal clades rece ive moderate bootstrap support．Further studies，especially DNA sequencing approaches， are needed before an unambiguous phylogeny is achieved for the genus．

Abstract:Based on the data investigated in the last decade and the survey of sampling plots of about 10 hm², the floristic composition of formation Dacrydium pierrei/Syzygium araiocladum was studied of tropical montane rain forest in Bawangling Nature Reserve located around the border between Changjiang and Baisha counties on Hainan Island. Three hundred and twenty six species in 137 genera and 61 families are involved. The dominant species and the number of species in main families as well as monotypic and oligotypic species are reviewed．The world distribution pattern of all taxa investigated is described and analysed． It is shown that tropical elements，in particular， tropical Asia elements are the main Ones ，followed by pantropic．Species and genera endemic to China are very limited，but monotypic and oligotypic genera are rich in the flora．

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Abstract:A species of Gramineae new to China, Eragrostis tephrosanthos Schult., is presented.

Abstract:This paper is based on a study of about 1000 specimens of mosses collected by Mr. Zhang Li and the authors in limestone area of northern Guangdong in 1990. The mossflora in this region consists of 187 species, 3 subspecies and 6 varieties in 110 genera and 40 families, among them Homalothecium laevisetum var. triplecatum is new to China, and Sinskea flammea ssp. ochracea and S. flammea ssp. rufifolioides are new to mainland of China. In this mossflora tropical and subtropical elements amount to 41.3%, East Asiatic elements comprise 33.7%, and North temperate elements and elements endemic to China represent 14.7% and 3.5% , respectively．It is very interesting that 8 genera endemic to East Asia have been found in this region．A name list of bryophytes is given．

Abstract:The experiments were conducted in Dinghushan Biosphere Reserve, Guangdong Province, in monsoon evergreen broad-leaved forest community with species of Castanopsis chinensis, Schima superba and Cryptocarya concinna in & plots with 5m×5m each. In four of the & plots the shrub and herb layers were removed, and in the other four these layers were retained as control. Another 4 plots with 2m ×5m each were used in the experiment for investigation of the effect of cleaning litter. Measurements were made in September and December every year during 1994 to 1998 to investigate the speoes number，the number of individuals，and the height of all newly appeared seedlings The results showed that the seedling establishment increased in plots removing shru b and herb layer or cleaning the litter， but the species richness of seed lings did not increase． High mortality of seed lings appeared in dry season and in plots with high light intensity Precipitaiton is a key factor affecting the establishment of seed lings．Moist soil condition could promote seed germination and seedling establishment．

Abstract:The characteristics of species diversity of Carpinus pubescens community and its successional community on the karst mountains in an area of 1 600 m~2 in Guiyang, Guizhou Province, were analysed using the formulas of Simpson's and Shannon-Weiner's indices, and evenness. The individual number, plant height and breast height diameter (DBH) of all trees higher than 2.5 cm in DBH were measured. The two indices were further estimated by the jackknife procedure. The results showed that Simpson's index of the community ranged from 1.14 to 3.88，Shannon-Weiner’S index from 0.50 to 2.43, and evenness from 0.19 to 0.71. With the development and succession of the community．the species diversity showed a trend of high→low→high．The jackknifing estimation value of Simpson’s index of the community ranged from 1.14 to 3.88, and its estimation interval from 1.O4 to 5.10，while of Shannon-Weiner's index ranged from 0.52 to 2.58．and its estimation interval from 0.24 to 3.14. The jackknife method is suggested to be a more effective too1 for estimating the index of species diversity．

Abstract:Ultrastructural observations on programmed cell death of nucellus in Pennisetum squamulatum demonstrate that the chromatin of the nucleus of the cell in apoptosis shows a condensation process and that the nuclear envelope becomes swollen by the outer membrane heaving. The inner membrane of nuclear envelope develops some protrusions into the swollen space. The endoplasmic reticulum cisternae dilate. Mitochondria are found to lose cristae.

Abstract:Green globular bodies (GGB) first obtained from runner tips of Nephrolepis cordifolia Presl were cultured on MS medium supplemented with 4 mg L^-1 BA and 0.1 mg L^-1 IAA at 23 ℃ under continuous fluorescent light at 40 μmol m^-2s^-1 for 30 days. These GGB were then subcultured on the same medium every month. The differentiation and the growth of GGB subcultured on varies media or with different growth regulators, and various light quality and light intensity were examined and calculated after 70 days. The results showed that stimu1ating effects on the differentiation and growth were observed at irradiance of lO0 μmol m^-2s^-1．Red light was better for differentiation of GGB than blue or white light．In addition，MS medium supplemented with 1 mg L^-1 6-BA and 200 mg L^-1 NaH₂PO₄ was best for differentiation of GGB．

Abstract:One to 2-year-old seedlings of two lychee (Litchi chinensis Sonn.) cultivars (droughtsensitive Chenzi and drought-resistant Dongliu 1) were planted in pots by moisture stress and normal watering to determine the relative water content (RWC) and the H⁺-ATPase activities in leaves. The effects of water stress on (specific) activity of cytoplasmic, ionically and covalently wall-bound H⁺-ATPase in leaves were studied. The results showed that RWC in leaves decreased with increasing water stress, but such decrease was 1ess in drought-resistant cultivar than in drought-sensitive one． The activities of cytoplasmic， covalently wal1-bound and ionically wall-bound H⁺-ATPase were 81.8O％-83.15％-11.48％-12.3O％ and 5.37％-5.9O％ of the total H⁺-ATPase activity, respectively．No significant difference was observed between two cultivars． Under water stress, the (specific1) activities of cytoplasmic, ionically wall-bound and covalently wall-bound H⁺-ATPase in leaves increased． The extent of increase was higher in drought-resistant cultivar than in drought-sensitive one．

Abstract:Essential oil, extracted from the rhizomes of ginger, was analysed by GC-MS. Thirty-five, 36 and 44 constituents were identified respectively from the methanol, ethyl acetate and hexane extracts. Principal constituents detected in the three extracts were terpenes, but the composition and contents of the terpenes were different. The contents of total terpenes and sesquiterpenes increased with increasing polarity of the solvents used for extraction, but the content of monoterpenes decreased. The contents of unsaturated sesquiterpenes with antioxidant activity increased with increasing polarity of extracting solvents．It is shown that the antioxidant activity of ginger extracts increases with increasing polarity of solvents used for extraction．

Abstract:Bauhinia championii lectin (BCL) was purified from the seeds of Bauhinia championii Benth. by affinity chromatography on an acid-treated Sepharose 6B column. Hemagglutinating activity of the purified BCL increased by 57 times and the activity recovery was 63.3%. The molecular weight of BCL is 64000 consisting of two identical subunits. The subunit molecular weight is 32000 with isoelectric point of 4.70. BCL is a glycoprotein containing 3.0% of sugar. N-acetyl-D-galactosamine was determined to be a most potent inhibitor of BCL in agglutinating rabbit erythocytes.

Abstract:The embryos, endosperm and young leaves of 3-month-seedling of Ginkgo biloba L. were used as explants for callus induction experiment. Calli induced from embryos on MS medium supplemented with 3 mg L^-1 NAA and 5 mg L^-1 KT gave highest growth rate (100%), whereas calli induced from endosperms on MS with 3 mg L^-1 NAA and 2 mg L^-1 KT gave 42.3% growth rate. MS with 1 mg L^-1 NAA and 3 mg L^-1 BA was best for callus induction from leaves. The content of flavonoid compounds was highest in calli from embryos, and lowest in calli from embryos, and lowest in calli from endosperms.

Abstract:The fluctuation of plant community means that the seasonal or annual fluctuation of a plant community. The characteristics of plant community fluctuate with the seasonal or annual changes in ecological factors. Fluctuation of plant community is one of key contents in the study on plant dynamics. The paper reviews the concept, causes, types, characteristics, measurement and mechanism of fluctuation in plant community.

Abstract:Studies of the genus Phaeocystis, a most widespread marine Prymnesiophyceae, are reviewed. The taxonomy of this genus remains unclear so far. Taxonomic criteria of species are based on initial colony shapes, geographic distribution, free-living cell characteristics as well as chemical products, ploidy, genome size, 18rRNA and so on. Based on all of these taxonomic characters, Phaeocystis has been divided into four definite species at present: P. scrobiculata, P. antarctica, P. globosa and P. pouchetii. The first has only free-living cells and forming no colony，while the rest are of co lony-forming species with not only single cell but also co lonies composed of thousands of cells em bed ded in one mucilaginous matrix occasionally reached several mm in diameter．Phaeocystis has a complex heteromorphic life cycle exhibiting alternation between two different morphological forms：free-living cells and colonies．The unicellular stage involves several types：non-motile．flagellates， microzoospores and possibly macrozoospores ．However，their respective function within Phaeocystis life cycle and，in particular，their involvement in colony formation are not completely.